Variable torque generation electric machine employing tunable halbach magnet array

ABSTRACT

An) electric machine with variable torque generation having a tunable Halbach array configuration. The electric machine includes a magnet assembly for generating a magnetic field. The magnet assembly includes a plurality of fixed magnets disposed in a ring arrangement so that fixed magnets having a north pole faced toward the rotor or stator are alternated with fixed magnets having a south pole faced toward the rotor or stator, a plurality of rotatable magnets disposed within a respective slot formed between two adjacent fixed magnets, a drive assembly for turning the rotatable magnets within the slots to vary the magnetic field generated by the magnet assembly in the rotor or stator, the drive assembly configured to turn the rotatable magnets between a first position wherein the magnetic field in the rotor or stator is augmented and a second position wherein the magnetic field in the rotor or stator is cancelled.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. § 119(e) of U.S.Provisional Application Ser. No. 62/984,270, filed Mar. 2, 2020, andtitled “Variable Torque Generation Electric Machine Employing TunableHalbach Magnet Array.” The present application claims priority under 35U.S.C. § 119(e) of U.S. Provisional Application Ser. No. 62/077,243,filed Sep. 11, 2020, and titled “Cascade Mosfet Design for VariableTorque Generator/Motor Gear Switching.” The co-pending Non-Provisionalapplication Ser. No. ______ titled “Cascade Mosfet Design for VariableTorque Generator/Motor Gear Switching” dated Mar. 2, 2021 isincorporated by reference herein in its entirety. Furthermore, theco-pending Non-Provisional application Ser. No. ______ titled “CoolingSystem for Variable Torque Generation Electric Machine” dated Mar. 2,2021 is incorporated by reference herein in its entirety.

BACKGROUND

Electric machines are devices that use electromagnetic forces to convertelectrical energy to mechanical energy or mechanical energy toelectrical energy. Common electric machines include electric generatorsand electric motors.

Electric generators convert mechanical energy into electrical energy foruse in an external circuit such as a power grid, an electrical system ina vehicle, and so forth. Most generators employ a motive power source inthe form a rotary force (torque) such as the rotation of a shaft. Therotary force causes electric current to be generated in one or more wirewindings through interaction between magnetic fields created by magnetswithin the generator and the wire windings. Common sources of motivepower include steam turbines, gas turbines, hydroelectric turbines,internal combustion engines, and the like, which have a constant torqueand continuous rotational speed, expressed in Revolutions Per Minute(RPM).

Electric motors are mechanically identical to electric generators butoperate in reverse. Electric motors convert electrical energy intomechanical energy through the interaction between magnetic fieldscreated by magnets within the motor and electric current passing throughone or more wire windings to generate a motive force in the form ofrotation of the motor's shaft (i.e., a rotary force or torque). Thisrotary force (torque) is then used to propel some external mechanism.Electric motors are generally designed to provide continuous rotationand constant torque. In certain applications, such as in vehiclesemploying regenerative braking with traction motors, electric motors canbe used in reverse as generators to recover energy that might otherwisebe lost as heat and friction.

Increasingly, electric generators employed in renewable energytechnologies must operate at rotational speeds (RPM) and torque thatvary widely because the power sources used are variable, untimely, andoften unpredictable. Similarly, electric motors employed byenvironmentally friendly or green technologies must be capable ofproducing a range of rotational speeds (RPM) and torques. However, whileconventional electric generators and motors often demonstrateefficiencies ranging from ninety to ninety-eight percent (90%-98%) whenoperating near their rated rotational speed (RPM)) and torque, theefficiencies of these same generators and motors decreases dramatically,often as low as thirty to sixty percent (30%-60%) when they areoperating outside of their rated rotational speed (RPM) and/or torque.

DRAWINGS

The Detailed Description is described with reference to the accompanyingfigures. The use of the same reference numbers in different instances inthe description and the figures may indicate similar or identical items.Additionally, it will be appreciated by those of ordinary skill in theart that the concepts disclosed herein may be applied to various kindsof electric machines including, but not limited to, electric motors,electric generators, and/or electromechanical transmission systems.Thus, throughout this disclosure and in the claims that follow, the termelectric machine is used generally to describe any electromechanicaldevice capable of employing the concepts described herein, and it shouldbe appreciated that, unless otherwise so stated, that the term electricmachine may refer to an electric motor, an electric generator, anelectromechanical transmission system, combinations thereof (e.g., anelectric machine may comprise a motor/generator suitable for use in ahybrid vehicle employing regenerative braking), and so forth.

FIG. 1 is a side view illustrating an electric machine, in accordancewith an example embodiment of the present disclosure.

FIG. 2 is a perspective view illustrating of the electric machine shownin FIG. 1, in accordance with an example embodiment of the presentdisclosure;

FIG. 3 is a cross-sectional perspective view of the electric machineshown in FIG. 1, the electric machine having a housing, a rotorassembly, a stator assembly and a main axle, in accordance with anexample embodiment of the present disclosure;

FIG. 4 shows a further cross-sectional perspective view of the electricmachine shown in FIG. 3, showing the rotor assembly having a Halbachconfiguration in accordance with example embodiments of the presentdisclosure;

FIG. 5 shows a different cross-sectional perspective view of theelectric machine shown in FIG. 2 parallel to the main axis, showing thestator assembly and the rotor assembly in accordance with an exampleembodiment of the present disclosure;

FIG. 6 is a side view illustrating the rotor assembly of the electricmachine in FIG. 5, arranged in a Halbach array having two sets ofrotatable magnets, in accordance with an example embodiment of thepresent disclosure;

FIG. 7 is a perspective view illustrating the rotor assembly of theelectric machine in FIG. 6, arranged in a Halbach array in accordancewith an example embodiment of the present disclosure;

FIG. 8 is a perspective view of fixed magnets of the Halbach array ofthe rotor shown in FIG. 6 in accordance with example embodiments of thepresent disclosure;

FIG. 9 is a front view of fixed magnets of the Halbach array of therotor shown in FIG. 6 in accordance with example embodiments of thepresent disclosure;

FIG. 10 is a perspective view of the rotor assembly shown in FIG. 6,showing a magnet assembly and drive assemblies to rotate rotatablemagnets within the magnet assembly in accordance with exampleembodiments of the present disclosure;

FIG. 11 is a perspective view of the rotor assembly shown in FIG. 10,further showing the magnet assembly and drive assemblies in accordancewith example embodiments of the present disclosure;

FIG. 12 is a perspective view of a different embodiment of the rotorassembly, shown in FIG. 2, having a drive assembly and magnet-securingcaps around the periphery of the magnet assembly in accordance withexample embodiments of the present disclosure;

FIG. 13 is a perspective view of another embodiment of the electricmachine, in accordance with an example embodiment of the presentdisclosure;

FIG. 14 is a perspective view of a mounting bracket shown in FIG. 13having torque sensors in accordance with example embodiments of thepresent disclosure;

FIG. 15 is cross-sectional perspective view of the electric machineshown in FIG. 13, the electric machine having a housing, a rotorassembly, a stator assembly and a main axle, in accordance with anexample embodiment of the present disclosure;

FIG. 16 is a perspective view of an end cap of the axle shown in FIG. 13in accordance with an example embodiment of the present disclosure;

FIG. 17 is a side view illustrating the rotor assembly of the electricmachine in FIG. 15, arranged in a Halbach array having one set ofrotatable magnets in accordance with an example embodiment of thepresent disclosure;

FIG. 18 is a perspective view of the rotor assembly shown in FIG. 15,showing a main axle, a magnet assembly and drive assembly to rotaterotatable magnets within the magnet assembly in accordance with exampleembodiments of the present disclosure;

FIG. 19 is a perspective view of fixed magnets of the Halbach array ofthe rotor shown in FIG. 18 in accordance with example embodiments of thepresent disclosure;

FIG. 20 is a side view of fixed magnets of the Halbach array of therotor shown in FIG. 18 in accordance with example embodiments of thepresent disclosure;

FIG. 21 is a perspective view of the rotor assembly shown in FIG. 15,showing a magnet assembly and drive assembly to rotate rotatable magnetswithin the magnet assembly in accordance with example embodiments of thepresent disclosure; and

FIG. 22 is a perspective view of the rotor assembly shown in FIG. 15,showing a magnet assembly configured in a Halbach array, in accordancewith example embodiments of the present disclosure;

DETAILED DESCRIPTION Overview

Although the subject matter has been described in language specific tostructural features and/or process operations, it is to be understoodthat the subject matter defined in the appended claims is notnecessarily limited to the specific features or acts described above.Rather, the specific features and acts described above are disclosed asexample forms of implementing the claims.

The Detailed Description is described with reference to the accompanyingfigures. The use of the same reference numbers in different instances inthe description and the figures may indicate similar or identical items.Additionally, it will be appreciated by those of ordinary skill in theart that the concepts disclosed herein may be applied to various kindsof electric machines including, but not limited to, electric motors,electric generators, and/or electromechanical transmission systems.Thus, throughout this disclosure and in the claims that follow, the termelectric machine is used generally to describe any electromechanicaldevice capable of employing the concepts described herein, and it shouldbe appreciated that, unless otherwise so stated, that the term electricmachine may refer to an electric motor, an electric generator, anelectromechanical transmission system, combinations thereof (e.g., anelectric machine may comprise a motor/generator suitable for use in ahybrid vehicle employing regenerative braking, a generator suitable fora wind turbine, etc.), and so forth.

Motors and generators are designed for operation at a specific rotatablespeed and torque with a very narrow range of optimum efficiency Hightorque requirements in a motor or generator demand more powerfulpermanent magnets which in turn create a large back Electromotive Force(EMF) that is in turn overcome with high voltage and current. Whenrotatable speed and torque are constant, the motor or generator can bedesigned for optimum efficiency. Often, this efficiency can be wellabove ninety percent (90%). Thus, in the design and manufacture of suchmotors and generators, the stator core, core windings and permanentmagnets are all selected to act together, to produce the requiredtorque, rotatable speed (RPM), voltage, and current ratios at an optimumor threshold efficiency. Once these key components are selected andplaced in the motor or generator, they cannot be changed. Only the powerand speed of the driving force in a generator or the voltage andamperage of the electric current into the motor can be changed. However,when such motors or generators are put in service where the speed andtorque vary widely such as in land vehicles and/or wind or water poweredgenerators, the back EMF of the fixed magnets must still be overcomewhen the speed and torque requirements are less than the maximumdesigned for and the stator wiring sufficient and appropriately sizedwhen the speed and torque are greater than the maximum designed for.When they are not, the overall efficiency of the motor or generatordramatically drops in many cases to as low as twenty percent (20%) forelectric or hybrid vehicles, wind or water powered generators, and thelike.

The present disclosure is directed to variable torque generation (VTG)electric motors, electric generators and/or transmission systems thatare capable of operating with high efficiency under wide voltage andamperage operating ranges and/or extremely variable torque and rotatablespeed (RPM) conditions. Electric motors in accordance with the presentdisclosure, are well suited for use in technologies were motors producevariable torque and/or rotatable speed (RPM). Similarly, electricgenerators in accordance with the present disclosure are well suited foruse in technologies were variable torque and rotatable speed (RPM)conditions are common such as where variable environmental conditionssuch as inconsistent wind speed, untimely ocean wave movement, variablebraking energy in a hybrid vehicle, and so forth, are frequentlyencountered. Example technologies may include, for example, technologiesemploying renewable energy resources including wind power, hydroelectricpower, electric or hybrid vehicles, and so forth.

As previously discussed, the magnetic field of a rotor in permanentmagnet electric motors and generators is not adjustable but fixed. Thealternating flow of magnetic flux between the permanent magnets of therotor and the cores of the stator and the alternating flow ofelectricity in the wires of the stator core that determine how apermanent magnet motor or generator will operate. Where there is a smallamount of magnetic flux flowing between the rotor magnets and the statorcore, it is as if the rotor of the motor or generator was fitted withsmall or lower strength permanent magnets. If the amount of flux flowingbetween the rotor magnets and the stator core is large, the reverse istrue, the strength of the permanent magnets in the rotor of the motor orgenerator is higher. When small permanent magnets are used in the rotorof a motor, the wires in the stator core coils are sized with therequisite number of turns to produce a magnetic field in the statorteeth (or cores) that will efficiently react with the magnetic field ofthe rotor magnets to produce the optimum (or nearly optimum) flux flowbetween the rotor and the stator and optimum (or nearly optimum) torqueor rpm. In the case of a generator, the wires are sized with therequisite number of turns to efficiently accommodate the electricitygenerated by the alternating flux induced in the stator cores by thepermanent magnets on the rotating rotor. Motors and generators may havea different number of wire windings even if the size of their respectivepermanent magnets is the same. The wires and number of turns in a largepermanent magnet rotor is different from the wires and number of turnsin a small permanent magnet rotor, and the size of the output of the tworotors is significantly different.

The techniques described herein can dynamically change the output “size”of an electric machine such as a motor, a generator, a transmission, orthe like, by one or more of varying the magnetic field induced in thestator by switching multiple non-twisted parallel coil wires in thestator between being connected in all series, all parallel, orcombinations thereof, and correspondingly tuning (e.g., varying,adjusting, or focusing) the magnetic field of the permanent magnetsacting on the stator using a tunable Halbach magnet arrangement in therotor. The tunable Halbach magnet arrangement is comprised ofinterspersed fixed and rotatable magnets, which may be rotated to tunethe magnetic field strength of the magnet array. Additionally, astorque/RPM or amperage/voltage requirements change, the system canactivate one stator or another (in multiple electric machine unitsconnected to a common computer processor) within the rotor/stator setsand change from parallel to series winding or the reverse through setsof two (2), four (4), six (6), or more parallel, three phase,non-twisted coil windings. In this manner, the system can meet thetorque/RPM or amperage/voltage requirements of the electric machinewhile improving (e.g., increasing, optimizing, or nearly optimizing) itsefficiency.

This disclosure provides systems and methods for adjusting the magneticfield of the permanent magnet rotor in an electric machine such as anelectric motor, generator, or transmission. It does so by employing atunable Halbach magnet array configuration for tuning (e.g., varying,adjusting, and/or focusing) the magnetic field acting on the statorcores to meet the torque and speed (RPM) requirements of the electricmachine at any given time. By reducing or increasing the magnetic fieldacting on the stator core, the present techniques respectively reduce orincrease the back EMF. For example, in the case when the electricmachine is a motor, a reduction or an increase of back EMF may result inusing lower or higher voltage and amperage (power) to run the motor. Ifin another example, the electric machine is a generator, varying theback EMF of the magnetic field would vary the torque (e.g., wind speed)needed to turn the generator. The present disclosure allows the systememploying the electric machine to adjust the back EMF to meet varyingconditions and operate the electric machine at a greater efficiency overmuch wider ranges of torque than ever before possible. With thesecapabilities, the electric machine can control the strength of theinteraction of the magnetic fields of both the rotor(s) and the statorover a relatively uniform range of variable power requirements with highefficiency. The efficiency of any electric motor is dependent on thebalance between the electromagnetic field of the stator and theelectromagnetic field of the rotor interacting with the stator. Theinverter/controller in the electric machine can regulate the voltagecoming from an electrical source, such as a battery or other electricalsource, which in turn regulates the amperage in the stator coil wireswithin the capacity of the wires and voltage source. The electricmachine can switch between different wiring combinations, each wiringcombination having a different resistance. Each different resistance ofthe wiring combinations creates a different range of amperage turns, asthe inverter/controller in a computer processor increases the voltage ineach wiring configuration from low to high. The different wiringconfigurations are then configured, combined, and coordinated with thevoltage regulation so that the overall range of the amperage flowing inthe stator coils can be uniformly regulated (increased or decreased)over a greatly extended range as the computer processor switches thewiring from one configuration to the next correspondingly changing thevalue of the turns in the stator coils and the resulting magnetic fieldstrength. With the ability of the electric machine to focus or controlthe magnetic field of the rotor magnets interacting with the statorcoils over a much larger range from low to high by the movement of therotor or rotors with respect to the stator, the computer processor maybe configured to tune the magnetic field of the rotor with respect tothe stator a function of the turns in the stator coils so that the rotoris tuned to provide the optimum efficiency or balance between themagnetic fields of the stator coils and the rotor permanent magnets.

Changing the wiring and number of turns to modify the flux of a statorcore and the electricity flowing in a core coil wires is not as easy toadjust or vary as changing the flux flowing from the rotor permanentmagnets. This can be accomplished by separating the multi-phase statorwiring at a center tap or the three legs of a delta configuration andproviding multiple non-twisted parallel wires in the core windings foreach phase leg (and in some cases with wires of different size) with theability to switch and connect the multiple wires in all series, allparallel, and combinations of parallel and series configurations. Insome implementations, one or more wires may be disconnected to provideadditional configurations (e.g., dropping from a six-wire system to afour-wire system, or the like). In some implementations, the phasewindings are also switchable from a star or WYE (Y) configuration to adelta (e.g., triangle) configuration. In some implementations, thesystem can provide two separate multi-phase wiring configurations withseparate controllers on the same stator, and in some implementationsseparating the coils in each phase leg (including the multiple wirestherein) so that any of the stator phases in either separate multi-phaseconfiguration can be switched (e.g., using electronic switches) to beconnected in series, in parallel, or in combinations thereof, in eitherthe star (Y) or Delta configuration.

In embodiments, an electric machine can also be provided by joiningtogether a plurality of modular electric machine units (e.g., eachhaving respective stator(s) and rotor(s)) to vary the overall systemoutput. For example, the electric machine units can be joined togetherunder common control from a central processor where they may operatetogether for increased power or at least one can operate while anotheris in neutral. The electric machine units may also be configured toshift back and forth between the different series, parallel, orcombination (i.e., series and parallel) wiring and switchingcombinations to provide smooth transitions between the variouscombinations. The electric machine units can also be shifted back andforth between Delta or Star phase configurations with series/parallelswitching of the multiple wires in each phase.

In embodiments of this disclosure, any single electric machine unit mayhave any or all of the combinations of multiple wiring and switchingdescribed herein, including switching between Delta and WYEconfigurations, multiple wire windings in series or parallel or in setsof two or more wires in parallel connected to each other in series, andwhere the electric machine is multi-pole, the individual coils of aphase winding may be connected in series or parallel or in sets of twoor more coils in parallel connected to each other in series, providing awide range of voltage/amperage and torque/speed ratios in a singleelectric machine that is electronically reconfigurable to meet widelyvarying conditions. This feature coupled with an electronic shifting ofthe rotor magnetic field and the ability to focus the magnetic field ofthe rotor on the stator cores, provides an ability through a computersystem processor to select and quickly change the winding configurationof the stator to meet widely variable speed and torque requirements thatmay be placed on the electric machine at optimum (or near optimum orotherwise selected) energy efficiency.

The electric machine of the present disclosure may further include acooling system. The cooling system allows to incrementally reduce theresistance of stator coils using the series and parallel switching toincrease the amperage in the coils without baring significant losses.Cooling the wires will allow the wires to carry more amperage by as muchas five times their rated capacity. In comparison to a conventionalmotor or generator with a single conductor per phase, a cooledconventional electric machine may have its power increased throughcooling by as much as five times, where the electric machine may haveits power increased by as much as 30 times.

The cooling system of the present disclosure may include a sealed statorcore and coil fluid cavity with circulating cooling fluid, tubing forcirculating water or different fluid to reduce the temperature of thecooling fluid circulated within the fluid cavity, thermoelectricdevices, such as Peltier devices, in contact with the cooling fluid.

Detailed Description of Example Embodiments

FIGS. 1 through 21 illustrate an electric machine having a rotoremploying a tunable Halbach array configuration in accordance with thepresent disclosure. The Halbach array configuration allows the flux ofthe permanent magnets in the electric machine to be tuned (e.g., varied,adjusted, focused, etc.) to vary the induction of electricity in thecoils in controlled increments from maximum amperage and/or voltage tozero or near zero amperage and/or voltage. The electric machinecomprises a housing, a stator, and at least one rotor. The at least onerotor includes a circular Halbach array of magnets, comprising fixedmagnets having a semi-hourglass shape or cross-section (e.g., anI-shaped cross-section), and rotatable magnets having a cylindrical(round) shape or cross-section, wherein the rotatable magnets aredisposed between slots provided between adjacent ones of the fixedmagnets. The fixed magnets are mounted to a stator core around theperiphery of the stator core and are positioned by placing alternatingadjacent north poles and south poles facing outwards towards the stator.The rotatable magnets are diametrically magnetized. A minimal uniformclearance is provided between the interior walls of the fixed magnetsand outer walls of the rotatable magnets. The interior walls of thefixed magnets may be coated with a friction-reducing coating such as aTeflon™ or Delrin™ type material or other polymers that reduce frictionbetween surfaces.

Referring generally to FIGS. 1 through 5, an electric machine 100 isdescribed in accordance with an embodiment of this disclosure. As notedherein above, the term electric machine may refer to an electric motor,an electric generator, a transmission system, combinations thereof, andso forth.

As shown in FIGS. 3 through 5, the electric machine 100 includes ahousing 102, a main axle 104, a stator assembly 106, and a rotorassembly 108. The housing 102 comprises a stator chamber 103. The mainaxle 104 is disposed in the housing 102 and is rotatably connected tothe housing 102, for example, for example via one or more bearings thatsupport the axle 104. The stator assembly 106 is also disposed withinthe housing 102. The stator assembly comprises a stator core 110supporting a plurality of windings 112. FIGS. 6 and 7 show the rotorassembly 108. The rotor assembly 108 is coupled to the main axle 104,and is configured to rotate with respect to the stator assembly 106 toturn the main axle 104. The rotor assembly 108 comprises a rotor core114, a first magnet assembly 116, and a second magnet assembly 117.

As shown in FIG. 10, the first magnet assembly 116 includes a firstplurality of fixed magnets 118 disposed in a first ring arrangement 119,and a first plurality of rotatable magnets 120. In the embodimentillustrated, the fixed magnets 118 have a generally semi-hourglass shapeor cross-section (e.g., an I-shaped cross-section). As shown, theI-shaped fixed magnets 118 have concavely curved interior sides so thatslots 126 are formed between adjacent ones of the fixed magnets 118about the periphery of the rotor assembly 108. Each of the fixed magnets118 comprise a north pole 122 and a south pole 124. Adjacent fixedmagnets 118 are separated by a respective one of the slots 126. Each ofthe fixed magnets 118 is mounted to the rotor core 114 and oriented sothat its north pole is faced either outward toward the stator assembly106 and away from the rotor core 114 or inward toward the rotor core 114and away from stator assembly 106, while its corresponding south pole isfaced in the opposite direction, that is, inward toward the rotor core114 and away from the stator assembly 106 or outward toward the statorassembly 106 and away from rotor core 114. The differently orientedfixed magnets 118 are disposed in an alternating arrangement about therotor core 114 so that fixed magnets 118 having their north pole facingthe stator assembly 106 are interspaced between fixed magnets 118 havingtheir south poles facing the stator assembly 106.

Each of the plurality of rotatable magnets 120 are disposed within arespective slot 126 between two adjacent fixed magnets 118. In theembodiment illustrated, the rotatable magnets 120 comprise a generallycylindrical body having a first end 128 and a second end 130. Thecylindrical body of each rotatable magnet 120 comprises a first halfcylinder 132 and a second half cylinder 134 extending from the first end128 to the second end 130 of the cylindrical body of the rotatablemagnet 120. The first and second half cylinders, 132 and 134,respectively, correspond to the north pole of the rotatable magnet 120and the south pole of the rotatable magnet 120. In embodiments, therotatable magnets 120 may be single piece magnets extending the lengthof the stator 106, as shown in FIG. 17, or comprised of multiplerotatable magnets coupled together by an axle 121, the multiplerotatable magnets having their poles aligned in the same or a differentdirection.

The rotor assembly 108 further includes a first drive assembly 136 forturning the rotatable magnets 120 within the slots 126 between the fixedmagnets 118, causing the magnetic field generated by the magnet assemblyto vary. In the embodiment illustrated, the rotatable magnets 120 areaffixed to an axle 121 extending through the longitudinal center of therotatable magnets 120 for the length of the rotor assembly 108 andsufficiently beyond the end of the rotor assembly 108 to accommodate anaxle gear 123 on at least one end of the axle 121. In other embodiments,the axles 121 may be replaced or supplemented with other gears,bearings, or bushings fixedly connected to the first end 128 and secondend 130 of rotatable magnets 120.

Bearings or bushings connecting the axles 121 to the rotatable magnets120 may be mounted on a non-magnetic plate on either end of the rotorassembly 108, or at intermittent intervals over the length of the rotor.Other embodiments of the rotor assembly 108 may use a synthetic polymer,including but not limited to polytetrafluoroethylene (PTFE) or Teflon™,to line the inner surface of the round space between the first halfcylinder 132 and the second half cylinder 134 of rotatable magnets 120to minimize friction between the rotatable magnets 120 and the axles121.

The drive assembly turns the rotatable magnets in a first direction(e.g., clockwise) between a first position, shown in FIGS. 10 and 11,where the magnetic field in the rotor or stator is increased oraugmented and a second position (not shown) where the magnetic field inthe rotor or stator is cancelled. Rotating the north pole 132 of arotatable magnet 120 towards the center of a fixed magnet's north pole122 facing outwards away from the rotor core 114 increases the magneticfield of the rotor assembly 108. In contrast, rotating the north pole132 of a rotatable magnet 120 towards the center of a fixed magnet'ssouth pole 124 facing outwards of the rotor core 114 decreases thestrength of the magnetic field to zero or near zero (e.g., zero (0) ornear zero (0) gauss). Because the magnetic field of the rotor assembly108 can be varied over a wide range of magnetic field strength (gauss)output, the application requirements can be met in a more efficient waycompared to the prior art. The rotation of rotatable magnets 120 can bereversed in increments up to 180 degrees so that the respective northpoles 132 and south poles 134 of the rotatable magnets 120 face theradial planes of opposing-pole fixed magnets.

FIGS. 10 and 11 also show the second magnet assembly 117 having a secondplurality of fixed magnets 138 disposed in a second ring arrangement140, and a second plurality of rotatable magnets 142. In the embodimentillustrated, the fixed magnets 138 have a generally semi-hourglass shapeor cross-section (e.g., an I-shaped cross-section). As shown, theI-shaped fixed magnets 138 have concavely curved interior sides so thatslots 126 are formed between them. Each of the fixed magnets 138comprise a north pole 122 and a south pole 124 and are divided by arespective one of the slots 126. Each of the fixed magnets 138 ismounted to the rotor core 114 and oriented so that its north pole isfaced either outward toward the stator assembly 106 and away from therotor core 114 or inward toward the rotor core 114 and away from statorassembly 106, while its corresponding south pole is faced in theopposite direction, that is, inward toward the rotor core 114 and awayfrom the stator assembly 106 or outward toward the stator assembly 106and away from rotor core 114. are disposed within a respective slot 126between two adjacent fixed magnets 138. The rotatable magnets 142comprise a generally cylindrical body having a first end 128 and asecond end 130. The cylindrical body of a rotatable magnet 142 comprisesa first half cylinder 132 and a second half cylinder 134 extending fromthe first end to the second end of the cylindrical body of the rotatablemagnet. The first and second half cylinders, 132 and 134, respectivelycorrespond to the north pole and the south pole of the rotatable magnet.

The second magnet assembly 117 further includes a second drive assembly144 for turning the second plurality of rotatable magnets 142 within theslots 126 between the second plurality of fixed magnets 138, allowingthe magnetic field generated by the second magnet assembly 117 to vary.The second drive 144 assembly turns the rotatable magnets 142counterclockwise between a first position where the magnetic field isincreased and a second position where the magnetic field in the rotor orstator is cancelled. Rotating the north pole of a rotatable magnet 142towards the central radial plane of a fixed north pole magnet 122 facingoutwards of the rotor core 114 increases the magnetic field of theelectric machine 100. In contrast, rotating the north pole of arotatable magnet 142 towards the central radial plane a fixed south polemagnet 124 facing outwards of the rotor core 114 decreases the strengthof the magnetic field to near zero (e.g., near zero (0) gauss), allowingthe rotor assembly 108 to vary the magnetic field over a wide range ofgauss output. The rotation of rotatable magnets 142 can be reversed inincrements up to 180 degrees so that the respective north and southpoles of the round magnets face the radial planes of opposing-pole fixedmagnets.

In the present embodiment, the first magnet assembly 116 and the secondmagnet assembly 117 are adjacent to one another. The first magnetassembly and the second magnet assembly are arranged in alternatingorder. The first plurality of fixed magnets 118 having a north pole 122facing outwardly towards the stator assembly 106 are adjacent to fixedmagnets of the second plurality of fixed magnets 138 having a south pole124 facing outwardly towards the stator assembly 106. Similarly, fixedmagnets of the first plurality of magnets 118 having a south pole 124facing towards the stator assembly 106 are adjacent to fixed magnets ofthe second plurality of fixed magnets 138 having a north pole 122 facingtoward the stator assembly 106.

FIGS. 10 and 11 illustrate the rotatable magnets of the first pluralityof rotatable magnets 120 being coupled to the rotatable magnets of thesecond plurality of rotatable magnets 142, forming a plurality ofrotatable magnet assemblies 146. The rotatable magnet assemblies have afirst side 132 and a second side 134. Rotatable magnets from the firstplurality of rotatable magnets 120 may have the magnetic north poledisposed at the first side 132 of the rotatable magnet assembly, and asouth pole disposed at the second side 134 of the rotatable magnetassembly. Rotatable magnets from the second plurality of rotatablemagnets 142, may have a south pole disposed at the first side 132 of therotatable magnet assembly and a north pole disposed at the second side134 of the respective magnet assembly. Every other rotatable magnetassembly may be positioned at a rotation angle of 180 degrees withrespect to the next rotatable magnet assembly along the ringarrangements 119 and 140 of the rotor assembly 108.

In an embodiment, each one of the first and second rotatable magnetassemblies 120 and 142 include a drive assembly having a planetary gear148. The respective first and second drive assemblies 136 and 144 alsocomprise a ring gear 150 engaged to a motive device 152 through a drivegear 154. The motive device 152 can be a stepper motor, a hydraulicpiston, or any other radial or linear motion device known in the art.Different embodiments of the present invention may include more than onemotive devices on each side of the rotor assembly. The ring gear 150 isconnected to the planetary gear 148. As seen on FIG. 10 the motivedevice 152 turns the drive gear 154 which rotates the ring gear 150 toturn the planetary gear 148. The planetary gear 148 enables eachrespective rotatable magnet assemblies to turn the plurality ofrotatable magnets 120 and 146 within the slots 126 between the pluralityof rotatable fixed magnets 118 and 138. In alternative embodiments, theaxle gears 123 at the ends of rotatable magnets 120 may be turned byother transmission means other than ring gears, including but notlimited to meshing all round axle gears 123 together so that thealternate rotatable magnets 120 on either side of the fixed magnets 118rotate clockwise and counterclockwise in alternating order.

The main axle 104 may shaped to support one or more motive devices 152.Motive devices 152 may be positioned facing forward and facing backwardsparallel in respect to the longitudinal axis of main axle 104, dependingon the number of motive devices 152 used in different embodiments ofelectric machine 100. The main axle 104 may also support differentelectronic devices used to control the one or more motive devices, suchas but not limited to Printed Circuit Boards (PCB), power converters,combinations thereof, and so forth. The main axle 104 may also include arotational position indicator which may be positioned at an end of themain axle 104.

FIG. 13 shows a different embodiment of the housing 102 inside amounting bracket 156. The mounting bracket 156, shown in FIG. 14, isrotatably connected to the main axle 104 by means of bearings 158 atboth sides of the main axle 104. This configuration allows the housing102 to have free rotational movement in reference to the mountingbracket 156. The axle 104 includes an end cap 157 having a positionsensor 159 and a wireless communication device. The position sensor 159measures the RPM of the electric machine, and the wireless communicationdevice communicates and transmits commands to each motive device 152.Another possible configuration of the mounting bracket 156 includes butis not limited to a completely closed shroud. This enclosed shroudmounting bracket (not shown) would protect the electric machine fromenvironmental contaminants and weather conditions.

As shown in FIG. 14, the mounting bracket 156 may include torque sensorssuch as but not limited to two load cells 160 mounted on either side ofthe electric machine housing 102. The load cells 160 may measure tensionor compression to determine the torque of the electric machine in eitherdirection. This torque measurement may be used in addition to othermeasured parameters (e.g., rpm, etc.) to determine the power input oroutput of the electric machine 100.

A second embodiment of the electric machine 100 is illustrated in FIGS.13 through 22. In this second embodiment of the electric machine, therotor 302 includes a single magnet assembly 304. FIGS. 19 and 20 show aplurality of fixed magnets 306. The I-shaped fixed magnets are arrangedaround the perimeter of a rotor ring and are fixed to a conventionallaminated plate 307. Each fixed magnet 306 comprises a north pole and asouth pole, alternately facing radially outward from the central axis ofthe rotor 302 around the perimeter of the rotor ring. A plurality ofrotatable magnets 308 are located within slots 310 between the fixedmagnets 306. The slots 310 may be coated with a friction-reducingcoating such as a Teflon™ or Delrin™ type material or other polymersthat reduce friction between surfaces.

The rotatable magnets 308 on either side of a fixed magnet 306 aredesigned to be rotated in the opposite direction from one another,preferably but not limited to approximately 180 degrees. The rotatablemagnets 308 are rotated by means of a sprocket 312 fixedly connected tothe end of the rotatable magnets. Including the sprockets 312, the driveassembly 314 also includes two ring gears 316 and 318, and motivedevices 320. Each one of the ring gears 316 and 318 comprise teeth onits outer circumference, respectively turning the sprockets 312 on everyother rotatable magnet 308. In this embodiment the first ring gear 316turns the first set of rotatable magnets clockwise, while the secondring gear 318 rotates the second set of rotatable magnetscounterclockwise. The ring gears 316 and 318 are in turn rotatablyconnected to a respective motive device 320 by means of teeth around theinner circumference of each ring gear. A different embodiment may changethe direction of rotation for the first and second ring gears.

The embodiments referenced in this disclosure may include a magneticmetal laminate around the rotor core 322 as magnet-securing caps 324 tosecure the pluralities of fixed magnets to the rotor rings, as shown inFIG. 9. The magnet-securing caps 324 may be tangentially separated fromeach other by a gap 325 to focus the variable strength of the magneticfield of the combined rotor assembly 108 radially outwards towards thestator assembly 106. In different embodiments, the magnet securing capsmay be positioned continuously between the north and south poles, andnot separated by a gap. The magnetic metal laminate may be magnetic ironbut could be made of a different ferromagnetic material. The stator corematerial may be magnetic iron, another magnetic material, a non-magneticmaterial (e.g., aluminum, etc.) or any combination of magnetic andnon-magnetic materials.

The stator core material may be magnetic iron, another magneticmaterial, a non-magnetic material (e.g., aluminum, etc.) or anycombination of magnetic and non-magnetic materials. Differentembodiments of the present invention may include a metallic casing 326around the pluralities of rotatable magnets. The casing 326 may be madefrom stainless steel or other metallic alloys.

In other embodiments, the electric machine 100 may include fixed magnetsof different depths, shapes, and sizes. The fixed magnets in otherembodiments may also be spaced-apart at different distances from oneother to fit the rotatable magnets between them to produce a variablemagnetic field and desired induction of electric current in the statorcoils. In other embodiments the rotatable magnets may be cylindrical inshape, having a diameter relative to the depth of the fixed magnets thatwill produce a variable magnetic field and desired induction of electriccurrent in the stator coils.

In other embodiments, the electric machine 100 may include a rotordisposed within the housing having a rotor core supporting a pluralityof windings. The rotor assembly may be coupled to a main axle, and maybe configured to rotate with respect to a stator assembly. The statorassembly may comprise a stator core, having at least one magnetassembly, the at least one magnet assembly having a tunable Halbacharray configuration in accordance with the present disclosure.

It is to be understood that the term “stator” is used herein to describean element of the electric machine where the wire coils are located intowhich electric current is induced by the magnetic field of the permanentmagnets or is fed an electric current by other sources to produce amagnetic field EMF to interact with the magnetic field of the permanentmagnets. This could be a motor, a generator, or a linear motor includinglinear induction motors.

Although the subject matter has been described in language specific tostructural features and/or process operations, it is to be understoodthat the subject matter defined in the appended claims is notnecessarily limited to the specific features or acts described above.Rather, the specific features and acts described above are disclosed asexample forms of implementing the claims.

What is claimed is:
 1. An electric machine, comprising: a magnetassembly for generating a magnetic field in one of a rotor or a statorhaving a plurality of wire windings carrying an electric current, themagnet assembly comprising: a plurality of fixed magnets disposed in aring arrangement, each of the fixed magnets having a north pole and asouth pole and arranged within the ring arrangement so that fixedmagnets having a north pole faced toward the rotor or stator arealternated with fixed magnets having a south pole faced toward the rotoror stator and a slot is formed therebetween; a plurality of rotatablemagnets, each of the rotatable magnets having a north pole and a southpole and disposed within a respective slot formed between a fixed magnethaving a north pole faced toward the rotor or stator and a fixed magnethaving a south pole faced toward the rotor or stator so that therotatable magnet may rotate within the slot; and a drive assembly forturning the rotatable magnets within the slots to vary the magneticfield generated by the magnet assembly in the rotor or stator, the driveassembly configured to turn the rotatable magnets between a firstposition wherein the magnetic field in the rotor or stator is augmentedand a second position wherein the magnetic field in the rotor or statoris cancelled.
 2. The electric machine as recited in claim 1, whereinrespective ones of the fixed magnets are generally I-shaped havingconcavely curved sides so that the slot formed between each pair offixed magnets is generally cylindrical, the fixed magnets having aplurality of magnet-securing caps that focus the magnetic field of therotor assembly towards the stator assembly.
 3. The electric machine asrecited in claim 2, wherein respective ones of the rotatable magnetscomprise a generally cylindrical body having a first end and a secondend, the cylindrical body comprised of a first half cylinder comprisingthe north pole of the rotatable magnet and a second half cylindercomprising the south pole of the rotatable magnet, the first and secondhalf cylinders extending from the first end to the second end.
 4. Theelectric machine as recited in claim 1, further comprising a secondmagnet assembly comprising: a second plurality of fixed magnets spacedabout the outer face of the rotor core in a second ring arrangement,each of the fixed magnets of the second plurality of fixed magnetshaving a north pole and a south pole arranged within the second ringarrangement so that fixed magnets having a north pole faced toward thestator assembly are alternated with fixed magnets having a south polefaced toward the stator assembly, with a slot is formed therebetween; asecond plurality of rotatable magnets, respective ones of the rotatablemagnets of the second plurality of rotatable magnets having a north poleand a south pole and disposed within a respective slot formed between afixed magnet having a north pole faced toward the stator assembly and afixed magnet having a south pole faced toward the stator assembly sothat the rotatable magnet may rotate within the slot; wherein the driveassembly is configured for turning the rotatable magnets of the secondplurality of rotatable magnets within the slots formed in the secondplurality of fixed magnets to vary the magnetic field in the statorassembly, the drive assembly configured to turn the rotatable magnetsbetween a first position wherein the magnetic field in the statorassembly is augmented and a second position wherein the magnetic fieldin the stator assembly is cancelled.
 5. The electric machine as recitedin claim 4, wherein the second magnet assembly is adjacent to the firstmagnet assembly so that fixed magnets of the first plurality of fixedmagnets having a north pole faced toward the stator assembly areadjacent to fixed magnets of the second plurality of fixed magnetshaving a south pole faced toward the stator assembly and fixed magnetsof the first plurality of magnets having a south pole faced toward thestator assembly are adjacent to fixed magnets of the second plurality ofmagnets having a north pole faced toward the stator assembly.
 6. Theelectric machine as recited in claim 5, wherein the rotatable magnets ofthe first plurality of rotatable magnets and the second plurality ofrotatable magnets are coupled together to form a rotatable magnetassembly.
 7. The electric machine as recited in claim 6, whereinrespective ones of the rotatable magnet assemblies have a first side anda second side, wherein rotatable magnets of the first plurality ofrotatable magnets have a north pole disposed at the first side and asouth pole disposed at the second side, and rotatable magnets of thesecond plurality of rotatable magnets have a south pole disposed at thefirst side and a north pole disposed at the second side.
 8. The electricmachine as recited in claim 7, wherein every other rotatable magnetassembly is positioned at a rotation of one hundred and eighty degreeswith respect to the remaining rotatable magnet assemblies.
 9. Theelectric machine as recited in claim 8, wherein respective ones of thefixed magnets are generally I-shaped having concavely curved sides sothat the slot formed is generally cylindrical.
 10. The electric machineas recited in claim 9, wherein respective ones of the rotatable magnetsof the first plurality of rotatable magnets and the second plurality ofrotatable magnets comprise a generally cylindrical body having a firstend and a second end.
 11. An electric machine, comprising: a housing; anaxle disposed in the housing, the axle supported by at least one bearingassembly so that the axle may rotate with respect to the motor housing;a stator assembly disposed within the motor housing, the stator assemblycomprising a stator core and a plurality of wire windings supported bythe stator core; a rotor assembly coupled to the axle and configured torotate with respect to the stator assembly to turn the axle, the rotorassembly comprising; a rotor core having a generally cylindrical outerface, a magnet assembly for generating a magnetic field in the statorassembly, the magnet assembly comprising: a plurality of fixed magnetsspaced about the outer face of the rotor core in a ring arrangement,each of the fixed magnets having a north pole and a south pole andarranged in the ring arrangement so that fixed magnets having a northpole faced toward the stator assembly are alternated with fixed magnetshaving a south pole faced toward the stator assembly with a slot formedtherebetween, and a plurality of rotatable magnets, each of therotatable magnets having a north pole and a south pole and disposedwithin a respective slot formed between a fixed magnet having a northpole faced toward the stator assembly and a fixed magnet having a southpole faced toward the stator assembly so that the rotatable magnet mayrotate within the slot; and a drive assembly for turning respective onesof the rotatable magnets within the slots to vary the magnetic field inthe stator assembly, the drive assembly configured to turn the rotatablemagnets between a first position wherein the magnetic field in thestator assembly is augmented and a second position wherein the magneticfield in the stator assembly is cancelled.
 12. The electric machine asrecited in claim 11, wherein respective ones of the fixed magnets aregenerally I-shaped having concavely curved sides so that the slot formedis generally cylindrical.
 13. The electric machine as recited in claim12, wherein respective ones of the rotatable magnets comprise agenerally cylindrical body having a first end and a second end, thecylindrical body comprised of a first half cylinder comprising the northpole of the rotatable magnet and a second half cylinder comprising thesouth pole of the rotatable magnet, the first and second half cylindersextending from the first end to the second end.
 14. The electric machineas recited in claim 11, wherein respective ones of the rotatable magnetscomprise a planet gear, and wherein the drive assembly comprises a ringgear engaged with the planet gears and a motive device having a drivegear engaged with the ring gear, wherein the motive device turns thedrive gear, rotating the ring gear to turn the planet gear, rotating therotatable magnet within the slot.
 15. The electric machine as recited inclaim 11, further comprising a second magnet assembly comprising: asecond plurality of fixed magnets spaced about the outer face of therotor core in a second ring arrangement, each of the fixed magnets ofthe second plurality of fixed magnets having a north pole and a southpole arranged within the second ring arrangement so that fixed magnetshaving a north pole faced toward the stator assembly are alternated withfixed magnets having a south pole faced toward the stator assembly, witha slot is formed therebetween; a second plurality of rotatable magnets,respective ones of the rotatable magnets of the second plurality ofrotatable magnets having a north pole and a south pole and disposedwithin a respective slot formed between a fixed magnet having a northpole faced toward the stator assembly and a fixed magnet having a southpole faced toward the stator assembly so that the rotatable magnet mayrotate within the slot; wherein the drive assembly is configured forturning the rotatable magnets of the second plurality of rotatablemagnets within the slots formed in the second plurality of fixed magnetsto vary the magnetic field in the stator assembly, the drive assemblyconfigured to turn the rotatable magnets between a first positionwherein the magnetic field in the stator assembly is augmented and asecond position wherein the magnetic field in the stator assembly iscancelled.
 16. The electric machine as recited in claim 15, wherein thesecond magnet assembly is adjacent to the first magnet assembly so thatfixed magnets of the first plurality of fixed magnets having a northpole faced toward the stator assembly are adjacent to fixed magnets ofthe second plurality of fixed magnets having a south pole faced towardthe stator assembly and fixed magnets of the first plurality of magnetshaving a south pole faced toward the stator assembly are adjacent tofixed magnets of the second plurality of magnets having a north polefaced toward the stator assembly.
 17. The electric machine as recited inclaim 16, wherein the rotatable magnets of the first plurality ofrotatable magnets and the second plurality of rotatable magnets arecoupled together to form a rotatable magnet assembly.
 18. The electricmachine as recited in claim 17, wherein respective ones of the rotatablemagnet assemblies have a first side and a second side, wherein rotatablemagnets of the first plurality of rotatable magnets have a north poledisposed at the first side and a south pole disposed at the second side,and rotatable magnets of the second plurality of rotatable magnets havea south pole disposed at the first side and a north pole disposed at thesecond side.
 19. The electric machine as recited in claim 18, whereinevery other rotatable magnet assembly is positioned at a rotation of onehundred and eighty degrees with respect to the remaining rotatablemagnet assemblies.
 20. The electric machine as recited in claim 19,wherein respective ones of the fixed magnets are generally I-shapedhaving concavely curved sides so that the slot formed is generallycylindrical, and wherein respective ones of the rotatable magnets of thefirst plurality of rotatable magnets and the second plurality ofrotatable magnets comprise a generally cylindrical body having a firstend and a second end.